The invention relates to an application mechanism for a disc brake, particularly for a sliding-caliper disc brake having an application shaft parallel to the brake rotor plane, which shaft engages against a thrust piece which can be moved toward the rotor, on the side of the shaft directed toward the rotor, and an element disposed on the side of the application shaft directed away from the rotor, which element serves as a support for the application shaft and with respect to which element the thrust piece can be moved.
The engagement against the thrust piece on the side of the application shaft directed toward the rotor therefore is such that the shaft is de-coupled from the thrust piece with respect to rotation of the shaft around a first rotational axis parallel to the longitudinal axis of the shaft, but the shaft is coupled with the thrust piece with respect to translational movement of the first rotational axis parallel to a plane defined by the brake rotor.
The support of the application shaft by the abovementioned support element on the side of the application shaft directed away from the brake rotor is such that the application shaft is coupled to the support element with respect to rotation of said application shaft around a second axis disposed parallel to the longitudinal axis of the application shaft, which second axis does not coincide with the first axis.
A brake application mechanism of the type described above is known from Ger. OS 40 32 885 A1. In the known mechanism, the application shaft is supported on it's side directed away from the brake rotor by means of a cylindrical inner contour in a corresponding bearing seat in the support element, wherein the seat is on the caliper housing. Consequently, a coupling is provided between the application shaft and the caliper housing with respect to translational movement of the second axis in a direction parallel to the plane defined by the brake rotor. This causes the thrust piece to tend to tilt in a plane perpendicular to the plane of the brake rotor, when the application shaft is rotated.
The resulting inclination of the thrust piece in its guide space leads, in turn, to inclination of the brake pads when the brake is engaged, which is detrimental to tile braking process and in addition causes nonuniform wear of the brake pads.
In the brake application mechanism disclosed in Ger. Pat. 2,614,321 C2, Eur. Pat. 0,291,071 B1, Ger. OS 34 11 745 A1, and Ger. Pat 2,057,322 C3, the application shaft and thrust piece are respectively de-coupled by suitable means to avoid tilting of the thrust piece. These means involve a sphere, and a transversely slidable plate or rod between the application shaft and the thrust piece. However, this configuration does not allow the application shaft and thrust piece to be held together and guided together. Thus, with these state-of-the-art application mechanisms, flexible holding means are required for the application shaft, e.g., spring(s) 86 in Ger. Pat. 2,614,321 C2. This, in turn, causes instability in the position of the application shaft, with consequent nonuniform brake-application. Further, with, e.g., the application mechanism according to Ger. Pat. 2,057,322 C3, the force application to the thrust piece is not always at the same locus. Rather, the locus of the force application moves with the position of the roll 7 in the groove 9.
U.S. Pat. No. 4,544,045 discloses a brake application mechanism having an application shaft which is linked, by means of rocking elements, on one side to a thrust piece and on the other side to the caliper housing. The rotational axis of the rocking member on the side directed away from the brake rotor is de-coupled from the caliper housing with respect to swinging movement around the rocking-member's rocking axis. The application shaft is rotatably mounted in the caliper housing with play existing parallel to the plane of the rotor.